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Hotel Nogalhilton Geneve, Nov 11, 2001

LOT 35

Timekeeper with 3 ComplicationsBreguet, No 220, sold to Comte de Montalva on October 28, 1847, for 4,000 francs.Extremely rare, fine and important month-going, weight-driven astronomical long case regulator with one-minute passing striking, annual calendar and equation of time, accompanied by a certificate.

CHF 300,000 - 400,000

USD 185,000 - 250,000

Sold: CHF 311,500

C. Mahogany, glazed on both sides and the front with gilt borders, rectangular cresting above molded cornice supported by ormolu-mounted corbels with ormolu band above, paneled veneered plinth mounted with cast moldings. D. Silvered and matte, Roman hour chapter, outer minute divisions, subsidiary seconds ring at XII, cut out to show the escapement, sector for the equation of time with engine-turned center at VI. Blued steel Breguet hands. M. Rectangular, 21,2 x 18 cm, heavy brass plates, doubleweights, four-wheel train, massive brass-steel gridiron pendulum beating seconds, suspended from a double suspension spring mounted to a heavy brass bracket in the case with length-regulating knob, the bracket has also an adjustable device for preventing excessive swinging of the pendulum, heavy brass bob with length-adjustment knob, micrometric beat adjustment on the crutch, dead-beat anchor escapement with stone pallets and the depth of the engagement regulating device, striking every minute wth a hammer raised by a cam mounted on the escape wheel arbor, lever protruding at 9 o'clock for striking/silence, annular wheel with 365 ratchet teeth set in the lower part of the movement, driven by a click on a spring-loaded lever raised and released once a day by a cam mounted on an intermediate wheel connected to the hour wheel with the ratio 1:2. Equation cam mounted on the annular wheel controls a rack meshing with the equation hand pinion.Signed on the dial Breguet, on the movement Breguet & Compie, the movement also numbered.Dim. Height 2 meters, width half meter


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Grading System
Grade:
Case: 3

Good
Movement: 3*

Good

Overhaul recommended, at buyer's expense
Dial: 3 - 01

Notes

Of the 45 regulators listed in the Breguet archives, no more than 15 are long case regulators.What is an Equation of Time?The equation of time was developed to explain and compensate for the discrepancy between true solar time and mean solar time. The true solar day is the length of time between one local noon, when the sun is highest, and the next. The length of this day is not always 24 hours, as the hours between sunrise and sunset are not always the same. The variable rate of the true solar day is due to two factors: 1) the Earth's rotation around the Sun is an irregular elliptical course and 2) the tilt of theEarth's rotation axis relative to its orbit around the Sun. Our yearly calendar that we rely on is based on an equal length of days throughout the year. The mean solar day (or time told by a watch or clock), calculated by averaging all the days of the year, was invented by astronomers for convenience, so that the solar day would always be 24 hours. The true solar time and mean solar time coincide four times a year, April 16, June 14, September 1 and December 25. On these days, the Equation willqual zero. During the other 361 days, the equation of time must be used to indicate the difference between the two times, amounting to about 16 minutes at certain times of the year. The minimum difference occurs on November 1, with a loss of 16 minutes and 23 seconds; and the maximum occurs on February 11 with an increase of fourteen minutes and 20 seconds. These positive and negative values are the offset in the time of the local noon and those of sunrise and sunset. The equation of time is oftn represented by a figure 8, called an "analemma".The equation of time can be approximated by the following formula: E=9.87 * sin(2B) - 7.53 * cos(B)-1.5 * sin(B) Where B= 360 * (N-81) / 365 Where N=day number, January 1=day 1